I'm working towards a single tier system, and have a couple of questions:

1) Can I use a metal tube like a racking tube with a pump, rather than drill through the sides of my kettles? Since I have to pump up from the bottom of one kettle to the top of the next anyway, can I avoid drilling the holes, buying the fittings and cleaning them? Just dropping a draw tube in sounds easier. Does anyone do this? If not, why not?

It's going to be more of a pain in the ass trying to start and keep a siphon to the pump than if you just went ahead and converted your kettles. The pumps we all use are not going to be able to start the wort movement on it's own.